This invention relates to fighter aircraft and to means for preventing operational maneuvers thereof beyond prescribed load factor limits.
The latest fighter airplane can easily maneuver beyond the load factor limits defined in the flight manuals in the majority of the flight envelope. The current method used to preclude overloading the airframe is to define load factor limits as a function of gross weight, one limit for symmetrical maneuvering and another for unsymmetrical maneuvers. Most pilots are not cognizant of the engineering definition of "unsymmetrical maneuvers" which establishes the load factor limit nor can it be expected of the pilot to constantly compute the load factor limit for an aircraft with varying weight. As a result the pilot must derive some kind of conservative technique to determine the maximum load factor to attempt to stay within. In the case of the F-15 this has not been successful resulting in many inspection hours required from over "g" ing the aircraft.
There have been numerous incidents of pilots exceeding the published handbook (F-15 Flight Manual TO IF-15-1) acceleration limits on operational aircraft. This is compounded by the inaccuracy of the cockpit G meter reading when performing accelerated maneuvers and the wide range of gross weight capability of the F-15 aircraft. This situation is even further complicated by maneuver asymmetry, configuration variation limits, and the fact that the aircraft capabilities far exceed the structural design requirements. An intentional effort has been made to keep the F-15 operating limitations (published in the F-15 Flight Manual) as simple as possible. However, this approach tends toward unnecessarily restrictive limitations. The present invention overcomes the foregoing problem and limitations by continuously monitoring the significant parameters which contribute to loading the airframe structure, computing the allowable maneuvering load factor and/or lateral stick force and transmitting aural warning to the pilot of an approaching overloading condition. The aircraft capability in this way can be more fully utilized and overloading conditions are avoided.